The present invention relates to a squirrel-cage rotor of an asynchronous machine, in particular a die-cast rotor. The invention also relates to an asynchronous machine with a rotor of this type and a method for manufacturing a rotor of this type.
The following discussion of related art is provided to assist the reader in understanding the advantages of the invention, and is not to be construed as an admission that this related art is prior art to this invention.
Asynchronous machines normally have a cage rotor or squirrel-cage rotor. For this purpose rods are for example positioned in axially running grooves of the laminated core of the rotor. On the end faces of the laminated core the ends of the rods axially exiting the laminated core are each electrically connected to a cage ring. In the case of larger axles the resulting cage is usually implemented as a soldered or welded design with aluminum or copper rods and rings. With smaller shaft heights it is particularly advantageous here to manufacture the squirrel-cage winding as a die-cast design. This is usually done in aluminum or copper die-casting.
At comparatively high speeds the ends of the cage rods projecting on both sides out of the laminated core of the rotor and the cage rings connected thereto are subject to very high centrifugal force stress. Additionally, as a result of high temperatures that cause a thermal expansion of, among other things, the cage ring, and of the high centrifugal forces mentioned, the material is subject to a great deal of stress at the junction between rod and cage ring, which ultimately can result in cracks or even fractures in the material.
The existing solutions are either particularly costly to implement, because they consist of a plurality of different parts, or they are not entirely suitable for the vulnerable junction between rotor rod and cage ring.
It would therefore be desirable and advantageous to obviate prior art shortcomings and to provide an improved squirrel-cage rotor of an asynchronous machine for comparatively high speeds which is easy to manufacture and which likewise allows even existing squirrel-cage rotors to be retrofitted.